Unlike the first game, Mass Effect 2 won’t allow players to start the next playthrough with all the skills and attributes gained throughout the previous one. Addressing a question on BioWare’s forum, lead designer for Mass Effect, Preston Watamaniuk said that the main reason for this change was that the developers wanted to offer a, “smooth transition into Mass Effect 3.” His exact words after the jump.
“The short answer is no.
The reason is progression. We have been working very hard to make sure we design the abilities system to offer smooth progression into ME3 from ME2. Allowing double progression on characters makes that almost impossible. We have to have reasonable knowledge about where a character could end up finishing all content on a playthrough. We also want to offer choice of character build within specific classes.
We replaced that feature with playing after you were done because it preserves progression and allows for smoother downloading of PRC.”
Via Kotaku